10 Best Outdoor Tankless Water Heaters 2025 in the United States

The Rinnai RXP199iN is a highly efficient tankless water heater that can operate on either propane or natural gas, making it versatile in terms of energy source. With a flow rate of up to 11.1 gallons per minute (GPM), it can supply hot water for multiple fixtures simultaneously, which is great for larger households or outdoor uses where instant hot water is a necessity. Its BTU rating of 199,000 indicates strong heating performance.

One of its standout features is the Smart-Circ Intelligent Recirculation system, which learns your hot water usage patterns and optimizes the recirculation to save energy and reduce wait times for hot water. Additionally, the high energy efficiency rating (UEF .98) means lower operating costs over time.

Installation is an important consideration; while it requires professional installation, the Rinnai Central App offers support for setup and troubleshooting, which can ease the learning curve for users. The heater is also designed for durability and can be installed outdoors with the proper venting, making it suitable for various environments. There are a few potential drawbacks. The need for professional installation may add to the cost, especially for those who prefer DIY projects. The unit is relatively compact but weighs 58 pounds, which might be cumbersome for some to handle during installation. Additionally, while the WiFi connectivity is a modern touch, the Control-R module is sold separately, which may be an extra expense for those wanting smart home integration.

The Rinnai RX199iN Condensing Smart Sense Tankless Water Heater is a solid choice for those seeking an efficient and high-capacity hot water solution for their home. With a flow rate of up to 11.1 gallons per minute (GPM), this heater can handle multiple fixtures simultaneously, making it ideal for larger households or homes with high hot water demand. Its 199,000 BTU rating ensures that it heats water quickly, maintaining a steady supply.

Energy efficiency is a standout feature, boasting a UEF rating of .98, which means it can help lower energy bills compared to less efficient models. The compact design allows for versatile installation, either indoors or outdoors, with the necessary Versa Vent system. This flexibility is a significant advantage for users with limited space.

However, installation isn't a DIY project; it requires professional help, which could add to the overall cost. Additionally, while it has a robust warranty and support system, some users may find the initial purchase price higher than standard water heaters.

The Rinnai RX160iN is a versatile tankless water heater designed for both indoor and outdoor use, making it a flexible choice if you want installation options. It delivers up to 9 gallons per minute, enough to supply six fixtures at once, which should cover most household needs comfortably. Its high BTU rating of 160,000 means it can provide a strong temperature rise, keeping your water hot even in colder climates. The unit boasts an impressive energy efficiency rating (UEF 0.97), which helps save on energy bills over time. Installation requires a professional, especially for outdoor setups where the Versa Vent system and an outdoor vent cap are necessary for safe operation.

The product is built with durability in mind, suitable for outdoor weather conditions when installed properly. A helpful Quick Flush feature makes maintenance easier, potentially extending the unit's life. While the heater offers smart controls and optional WiFi connectivity for convenience, those features require additional purchase. The warranty and support from Rinnai are reliable, adding peace of mind.

At 54 pounds, it’s relatively heavy, and installation can be complex and costly if you don’t have a professional. Also, while the flow rate is good for most homes, very large households with high simultaneous water use might need a larger system. This model serves as a strong, efficient choice for those wanting a flexible, high-performance tankless water heater suitable for both indoor and outdoor installation.